Variable inductors are generally made from coils of conductor wires. To vary the inductance of such an inductor, a first solution consists in disposing a moving magnetic core in the center of the coil. A second solution, which is applicable particularly when the coil is merely a helix, consists in using a moving conductor component having one end which slides over the helix and whose other end constitutes one of the terminals of the variable inductor, with the other terminal of the variable inductor being constituted by one of the ends of the helix. These two types of embodiment are ill-suited to high power applications as occur, for example, in high energy pulse generators operating at voltages greater than 10 kV and at currents greater than 1 kA. It is not possible to use a moving core at very high currents because the magnetic material constituting it saturates.
It is also impossible to make a sliding contact for currents greater than a few hundred amps, since heating due to the passage of the current gives rise to surface melting of the two portions in contact, and consequently welds them together.
An object of the present invention is thus to provide a high power variable inductor. Such an inductor makes it possible, in particular, to vary certain characteristics of high energy pulse generators continuously, e.g. rise time.